Request for advice (re speaker surgery)

I've lurked here for quite a while, and read dozens of posts related to upgrades of vintage Polks. I'm finally ready to tackle my Monitor 7s, but have a few questions I hope can be answered.

1. The circular plastic cups on the back are screwed in place, but whatever is used as a seal is sure to be either shot by now, or destroyed once I remove them. What is the current thinking on what to use as a seal (from my reading, it appears Mortite is now discredited)

2. These have a lead soldered to the tweeter. It seems like a bad idea to heat this delicate part. Will sound quality be affected by snipping the lead, say at or near the crossover, then soldering them back together?
Or would it be better to unsolder them at the crossover board.

Thanks for any help you can offer.
«1

Comments

  • F1nutF1nut Posts: 43,594
    The gaskets are meant to be paper thin.

    Do not desolder the leads on the Peerless tweeter.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • slow_polk7slow_polk7 Posts: 13
    edited February 4
    F1nut wrote: »
    The gaskets are meant to be paper thin.

    Do not desolder the leads on the Peerless tweeter.

    First off, I thank you for your rapid response.

    But the question remains: what is the consensus on the correct material to use, if existing gasket deteriorated or destroyed in process?

    As to the second, by default I assume you are advocating cutting the lead to the tweeter or desoldering at the crossover board.

    May I ask which you are advocating?
  • nooshinjohnnooshinjohn Posts: 21,939
    The preferred replacement for the gasket material is a product called Armacell pipe tape, which can be found in roll form at Home Depot. I concur with Jesse on the Peerless tweets.
    The Gear... Carver "Statement" Mono-blocks, TriangleArt Reference SE with Pass Labs Xono Phono Preamp, Walker Precision Motor Drive, ClearAudio Goldfinger Diamond v2 cartridge and Origin Conquerer Mk3c tonearm, Polk Audio "Signature" Reference Series 1.2TL with complete mods, Pass Labs X0.2 three chassis preamp, PS Audio PerfectWave DAC MkII, Krell Evolution 505 SACD Player, Pioneer Elite SC-LX701, Oppo UDP-205 4K Blu-ray player, Sony XBR70x850B 4k, Polk audio AB800 "in-wall" surrounds.

    Saying that it's "too hard" to pursue your dreams is no different than admitting to yourself that you are too lazy to achieve them.

    “If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
  • nooshinjohn

    Thanks for your response.
  • FaustinFaustin Posts: 920
    If you are concerned about damaging the Peerless tweeter, then yes, cut it 6"-10" from the tweeter and resolder. Finish with a bit of heat shrink.
  • Thank you Faustin.
  • FWIW I cut mine 1-1/2" from the tabs and crimped on male fastons. Any solder joint is going to be more resistance than a good crimp joint. Remains to be seen over time where at some point the solder joint may be superior because it prevents corrosion. I use a little silver platelet conductivity grease on my crimps too though.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • GardenstaterGardenstater Posts: 396
    edited February 4
    @nooshinjohn I feel that stuff is WAY too thick for the tweeters. The stuff Polk/Peerless used is only ~0.015" thick uncompressed. I have asked for advice here on what to use and have not found anything suitable myself yet. I think the armacell is OK for the crossover assy seal. I'm not sure if it's too thick for the midbass and passives. May be ok but I'd prefer something thinner.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • pitdogg2pitdogg2 Posts: 15,539
    @nooshinjohn I feel that stuff is WAY too thick for the tweeters. The stuff Polk/Peerless used is only ~0.015" thick uncompressed. I have asked for advice here on what to use and have not found anything suitable myself yet. I think the armacell is OK for the crossover assy seal. I'm not sure if it's too thick for the midbass and passives. May be ok but I'd prefer something thinner.

    What you keep failing to realize is that it compresses down very easy and becomes the same as polks gasket material. FWIW years ago a former member made the exact gaskets like Polk originals they too were about 1/8" thick and they compressed down without much resistance and worked perfectly
  • Well, what happened when I tried it on the tweeters is that I saw the tweeter plate, which is made of aluminum I think, curve as the screws were tightened. I appreciate what you are saying but that makes me nervous as far as what effect it will have on the suspension of the silk dome tweeter. I think that where the MW basket frames and especially the passive basket are concerned, well they are much more robust and rigid as far as being able to compress the gasket evenly but the tweeter plate is not that rigid and the mounting screws are not evenly spaced relative to the silk dome suspension.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • mhardy6647mhardy6647 Posts: 24,463
    The gaskets are there to do the work of making the seal(s) -- there should be no need to over-tighten any of the screws.

    Just my opinion, I am -- ironically enough -- not an expert on re-habbing Polk loudspeakers, even though I've owned at least a pair since 1978. :p

  • GardenstaterGardenstater Posts: 396
    edited February 4
    Absolutely. Do not *overtighten* ever. My Polk 7Bs have the Peerless tweets sitting .015" sub flush with the front baffle, as they came from the factory. When it comes to the other drivers, the object of Larry's Rings etc. is to make the baffle to speaker basket frame as firm as possible, which argues for thin gaskets being best, and the torque of the screws should be just enough to achieve that.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • @nooshinjohn I feel that stuff is WAY too thick for the tweeters. The stuff Polk/Peerless used is only ~0.015" thick uncompressed. I have asked for advice here on what to use and have not found anything suitable myself yet. I think the armacell is OK for the crossover assy seal. I'm not sure if it's too thick for the midbass and passives. May be ok but I'd prefer something thinner.

    Just to be clear -- my original post was indeed about the seal for the x-over cup.
    I don't see any reason to disturb the actual speakers; I just want to rebuild the x-overs.

    btw - interesting comment about crimps vs soldering; can't say I agree, but not saying I'm right.
  • pitdogg2pitdogg2 Posts: 15,539
    Well, what happened when I tried it on the tweeters is that I saw the tweeter plate, which is made of aluminum I think, curve as the screws were tightened. I appreciate what you are saying but that makes me nervous as far as what effect it will have on the suspension of the silk dome tweeter. I think that where the MW basket frames and especially the passive basket are concerned, well they are much more robust and rigid as far as being able to compress the gasket evenly but the tweeter plate is not that rigid and the mounting screws are not evenly spaced relative to the silk dome suspension.

    Interesting as I used it on multiple tweeters, drivers and passive radiators and I have never experienced that. It compressed so easily I had a fear it would not work.

    Just so we are comparing apples this is what you looked at

    https://www.homedepot.com/p/Armacell-2-in-x-30-ft-R-1-Foam-Insulation-Tape-TAP18230/100539553?mtc=Shopping-B-F_D26P-G-D26P-26_2_AIR_CIRCULATION_ACCES-Generic-NA-Feed-LIA-NA-NA-GeneralAirCirc&cm_mmc=Shopping-B-F_D26P-G-D26P-26_2_AIR_CIRCULATION_ACCES-Generic-NA-Feed-LIA-NA-NA-GeneralAirCirc-71700000052572800-58700005047686952-92700050204970713&gclid=EAIaIQobChMI1a3uorK45wIVcyCtBh3apgv_EAQYASABEgLZhfD_BwE&gclsrc=aw.ds
  • GardenstaterGardenstater Posts: 396
    edited February 4
    This is the stuff I used. Meant for insulating pipes. Had some from insulation work years ago. http://www.armacell.us/products/armaflexinsulationtape/


    Perhaps they have made it cheaper and it is more compressible now.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • @slow_polk7

    Crimping
    RAM Crimp toolCrimping was invented by Amp Incorporated in 1941 as a solderless method for terminating wires and connectors. Crimping technologies enabled far more rapid and consistent wire terminations compared to soldering. Over the years many different methods of crimping technology were invented for single wires, multiple wires and coaxial cables. While most people assume a "crimp" is just a contact crushed onto a wire, giving electrical conductivity by means of pressure, real crimping involves "elastic" and "plastic" deformation and flow of metals resulting in "micro cold welds" due to "contact asperity welding" of the metal surfaces. During the deformation process the wire and connector are mechanically cleaned, usually making pre-cleaning of wire and terminal unnecessary. When done right, this crimped connection can be much stronger and longer lasting than a soldered connection, and have electrical resistance of the equivalent length of wire. A properly done crimp is also gas-tight as well, not allowing oxidation to degrade it over time.

    https://www.audioholics.com/audio-video-cables/crimping-and-soldering


    Solder actually has much higher resistance than copper, even so-called silver solder. Most people use way too much solder, rather than the minimal amount which even compounds the problem. Soldering is definitely an art form.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • slow_polk7slow_polk7 Posts: 13
    edited February 5
    Gardenstater

    Very informative. Do you have terminals and crimp tool of choice --- ones that you'd recommend?
  • F1nutF1nut Posts: 43,594
    This is bordering on ridiculous. Do you know how many soldered joints are in every piece of gear you own!?!
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."


    President of Club Polk

  • nooshinjohnnooshinjohn Posts: 21,939
    This is the stuff I used. Meant for insulating pipes. Had some from insulation work years ago. http://www.armacell.us/products/armaflexinsulationtape/


    Perhaps they have made it cheaper and it is more compressible now.

    I have used the stuff on three sets of SDA’s, tweets and every other component requiring a gasket with zero difficulty for years now. Never had an issue.

    The Gear... Carver "Statement" Mono-blocks, TriangleArt Reference SE with Pass Labs Xono Phono Preamp, Walker Precision Motor Drive, ClearAudio Goldfinger Diamond v2 cartridge and Origin Conquerer Mk3c tonearm, Polk Audio "Signature" Reference Series 1.2TL with complete mods, Pass Labs X0.2 three chassis preamp, PS Audio PerfectWave DAC MkII, Krell Evolution 505 SACD Player, Pioneer Elite SC-LX701, Oppo UDP-205 4K Blu-ray player, Sony XBR70x850B 4k, Polk audio AB800 "in-wall" surrounds.

    Saying that it's "too hard" to pursue your dreams is no different than admitting to yourself that you are too lazy to achieve them.

    “If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
  • @slow_polk7 I think if you carefully work around the crossover cups with a putty knife or the like, with a beveled edge, you'll be able to remove them with the existing gaskets undamaged and re-usable. That's how it has always gone for me with my 7Bs.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • @FInut Jeezus. You're totally misconstruing my presenting what I though might be interesting info. about how cold weld type crimps can be superior to a silver soldered joint, for joining two wires together, or a faston to a wire etc., as my saying that soldered joints should be done away with in the construction of audio equipment. I didn't pull this out of thin air. It is well known to the audiophile community, and high end audio cable mfgs.
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • GardenstaterGardenstater Posts: 396
    edited February 5
    slow_polk7 wrote: »
    Gardenstater

    Very informative. Do you have terminals and crimp tool of choice --- ones that you'd recommend?

    Nope. Still figuring this stuff out myself. Clearly though it's not a one size fits all proposition and the tooling has to be precisely designed to fit the pieces being crimped. I do know that the more pressure the better as well.

    I have ordered the WBT Faston Terminals from partsconnexion.com in 2.8mm and 4.8mm. and am planning to try those. Haven't found any copper based male fastons yet so I'm making my own and plan to try crimping them onto the stub wire from my Peerless tweeters with the use of a copper crimping sleeve and the silver platelet conductivity enhancing grease (just a smidge). I have a crimping tool that has lots of mechanical advantage and is for crimping wire fishing leader sleeves.

    This tool is available from Parts Express for a mere $140 (lol) for crimping WBT crimping sleeves (0.5, 0.9, 1.5, 2.5, 4.0, 6.0, 10.0, 16.0 mm^2 (20 - 5AWG)

    zd2y36y80o26.png

    Fishing wire leader crimp tool (~16AWG to ~7AWG)

    drz9dqllj6su.jpg

    Post edited by Gardenstater on
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • skrolskrol Posts: 2,863
    edited February 6
    I suppose we could go back to wire wrap. It was reliable if done correctly.
    vnz0pjqtv716.jpgqox1gmbwivwp.jpg

    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW10 (DXi104 upgrade), Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7; Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • @skrol Yeah interesting. Then there's point to point wiring like in my buddy Steve's tube pre-amp where they are trying to avoid the higher resistance PCB copper traces. I know they are using solder still between the wires. Don't know if any mfg's have also gone the route of cold weld crimping those wire connections together. I rather doubt it......
    George / NJ

    Polk 7B main speakers (1979, orig owner)
    Martin Logan Dynamo sub
    Crown D150 amp
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14 gauge, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
  • Navy_GoatNavy_Goat Posts: 112
    skrol wrote: »
    I suppose we could go back to wire wrap. It was reliable if done correctly.
    qox1gmbwivwp.jpg
    This gives me flashbacks of working on the old AYK-10 mission computers. I don't even remember what they were in, but i do remember the masive wire wrap chassis. It was a nightmare......
    Main: Marantz NR-1509, Parasound HCA-1500a, Polk SDA 1C & 2BTL, Polk cs400i, SVS SB-13ultra.
    HT Room: HK AVR-75, Polk RT-16, csi40, FX500, 2xBic F1
    Office: Fiio E-17 DAC, Fiio K-5 Doc/Amp, JBL LSR 305, Audio Technica 700MKII, HiFiMan 400i
    Portable: Fiio X3ii, Shure SE-215, Fender FXA2/FXA6, MEE M6Pro
  • nooshinjohnnooshinjohn Posts: 21,939
    I don't even know how they could have designed it, much less built it.
    The Gear... Carver "Statement" Mono-blocks, TriangleArt Reference SE with Pass Labs Xono Phono Preamp, Walker Precision Motor Drive, ClearAudio Goldfinger Diamond v2 cartridge and Origin Conquerer Mk3c tonearm, Polk Audio "Signature" Reference Series 1.2TL with complete mods, Pass Labs X0.2 three chassis preamp, PS Audio PerfectWave DAC MkII, Krell Evolution 505 SACD Player, Pioneer Elite SC-LX701, Oppo UDP-205 4K Blu-ray player, Sony XBR70x850B 4k, Polk audio AB800 "in-wall" surrounds.

    Saying that it's "too hard" to pursue your dreams is no different than admitting to yourself that you are too lazy to achieve them.

    “If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.”
  • BlueBirdMusicBlueBirdMusic Registered User Posts: 805
    skrol wrote: »
    I suppose we could go back to wire wrap. It was reliable if done correctly.
    vnz0pjqtv716.jpgqox1gmbwivwp.jpg

    Then you would use a tool similar to the one below. I purchased one because my Pioneer pl-570 turntable used the wrap method (but soldered also because the pins were round) on power connections for the timing motor that I replaced.

    qutt60jaz9kk.png
  • drumminmandrumminman Posts: 3,374
    Re: solder, it is meant to reinforce the electrical connection. The wire should make good contact and the solder should be used for mechanical strength, not to promote current flow. At least that’s the way I’ve learned and always done it.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
  • slow_polk7slow_polk7 Posts: 13
    @drumminman

    That sounds logical enough, but one need only consider the case of a through-hole component on a PCB to realize that the solder is indeed responsible for current flow.
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